package cn.tedu.csmall.product.filter;

import cn.tedu.csmall.product.security.LoginPrincipal;
import cn.tedu.csmall.product.web.JsonResult;
import cn.tedu.csmall.product.web.ServiceCode;
import com.alibaba.fastjson.JSON;
import io.jsonwebtoken.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

/**
 * JWT过滤器
 *
 *
 */
@Slf4j
@Component
public class JwtAuthorizationFilter extends OncePerRequestFilter {
    @Value("${csmall.jwt.secret-key}")
    private String secretKey;
    public static final int JWT_MIN_LENGTH=113;
    public JwtAuthorizationFilter() {
        log.info("创建过滤器对象:JwtAuthorizationFilter");
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        log.debug("JwtAuthorizationFilter开始执行过滤!!!");

        //清空security上下文(非必要)
        //SecurityContextHolder.clearContext();
        //获取客户端携带的JWT
        String jwt = request.getHeader("Authorization");
        log.debug("获取客户端携带的JWT:{}",jwt);
        //检查是否获取到了基本有效的JWT
        if (!StringUtils.hasText(jwt)||jwt.length()<JWT_MIN_LENGTH){
            //对于无效的JWT,直接放行,交由后续的组件进行处理
            log.debug("获取到的jwt被视为无效,当前过滤器将放行...");
            filterChain.doFilter(request,response);
            return;
        }
        //尝试解析JWT
        log.debug("获取到的jwt被视为有效,准备解析JWT...");
        response.setContentType("application/json;charset=utf-8");
        Claims claims = null ;
        try {
            claims = Jwts.parser()
                    .setSigningKey(secretKey)
                    .parseClaimsJws(jwt)
                    .getBody();

        } catch (SignatureException e) {
            log.debug("解析JWT时出现SignatureException");
            String message="非法访问!";
            ServiceCode serviceCode=ServiceCode.ERR_JWT_SIGNATURE;
            JsonResult<Void> jsonResult=JsonResult.fail(serviceCode,message);
            String jsonResultString = JSON.toJSONString(jsonResult);
            PrintWriter writer = response.getWriter();
            writer.println(jsonResultString);
            return;
        } catch (MalformedJwtException e) {
            log.debug("解析JWT时出现MalformedJwtException");
            String message="非法访问";
            ServiceCode serviceCode=ServiceCode.ERR_JWT_MALFORMED;
            JsonResult<Void> jsonResult=JsonResult.fail(serviceCode,message);
            String jsonResultString = JSON.toJSONString(jsonResult);
            PrintWriter writer = response.getWriter();
            writer.println(jsonResultString);
            return;
        } catch (ExpiredJwtException e) {
            log.debug("解析JWT时出现ExpiredJwtException");
            String message="登录信息已过期!请重新登录!";
            ServiceCode serviceCode=ServiceCode.ERR_JWT_EXPIRED;
            JsonResult<Void> jsonResult=JsonResult.fail(serviceCode,message);
            String jsonResultString = JSON.toJSONString(jsonResult);
            PrintWriter writer = response.getWriter();
            writer.println(jsonResultString);
            return;
        } catch (Throwable e){
            log.debug("解析JWT时出现Throwable，需要开发人员在JWT过滤器补充对异常的处理");
            e.printStackTrace();
            String message = "你有异常没有处理，请根据服务器端控制台的信息，补充对此类异常的处理！！！";
            PrintWriter writer = response.getWriter();
            writer.println(message);
            return;

        }
        //获取JWT中的管理员信息
        String username = claims.get("username", String.class);
        Long id=claims.get("id",Long.class);
        String authoritiesJsonString = claims.get("authoritiesJsonString", String.class);
        log.debug("从jwt中获取id:{}",id);
        log.debug("从jwt中获取username:{}",username);
        log.debug("从jwt中获取authoritiesJsonString:{}",authoritiesJsonString);
        //处理权限信息
        List<SimpleGrantedAuthority> authorities
                = JSON.parseArray(authoritiesJsonString, SimpleGrantedAuthority.class);

        //创建Authorization对象
        LoginPrincipal loginPrincipal=new LoginPrincipal(id,username);
        Authentication authentication =new UsernamePasswordAuthenticationToken(
               loginPrincipal,null,authorities
        );
        //将Authorization对象存入到securityContext
        log.debug("向securityContext中存入认证信息:{}",authentication);
        SecurityContextHolder.getContext().setAuthentication(authentication);

        //过滤器继续向后传递:放行
        log.debug("过滤器执行完毕,将放行!");
        filterChain.doFilter(request,response);
    }
}
